1. Field of the Invention
This disclosure describes mechanical mechanisms that mechanically prevent a rotor from rotating below a threshold speed, but allow the rotor to rotate freely above the threshold speed.
2. Description of Related Art
The rotary wing aircraft, or helicopter, is one common type of vertical takeoff and landing (VTOL) aircraft. VTOL aircraft have large rotors that provide either or both vertical and horizontal thrust. Often, when a rotor is not being used, the rotor is kept stationary.
Conventional systems typically use a motor that is coupled to the rotor and adapted to prevent the rotor from rotating when it is not in use. The motor applies a torque to keep the rotor stationary. Thus, conventional systems require the supply of energy to the motor in order to reject disturbance torques that would cause the rotor to rotate. Supplying the energy required to keep the rotor stationary drains energy from a battery that provides the energy to the motor and also causes the motor to generate unwanted heat.